The invention relates to a binocular telescope with a focusing member in each barrel, which serves for the focusing and which is joined to a support guided in a guide rod and axially displaceable by a transmission bar via a control knob.
A binocular telescope with common focusing of the two individual telescopes is known from DE-AS 2,316,955, in which the optical components serving for the focusing comprise a support, inside the tube, which is axially adjustable by means of a control knob arranged outside. Rotation of the control knob is transmitted, via a screw rod connected thereto, to a transverse web rotatably connected to a rod which, in turn, is fixedly connected to the support. This support consists of a cylinder surrounding the rod, a connecting web and a conical component comprising a focusing-lens support.
By a rod-shaped guide element for the support, a rotation of the focusing lens from out of the optical axis is prevented. However, a guidance free from play and a tilt-free arrangement of the focusing-lens support are not ensured.
A binocular telescope with an articulated bridge and a central focusing device is, furthermore, known from DD-PS 108,385 in which the central focusing shaft is provided in its central region with an external screwthread on which a threaded bush is mounted so as to be adjustable by upward rotation. This threaded bush is joined coaxially and completely secured to a driving gear with which the focusing can be carried out. The threaded bush and the driving gear form an annular groove in which two identical rings, which are provided with a pin, are mounted superposed. These rings engage in bores in the casing of a focusing member. In order to prevent play between pin and bore, the pins have a slot which can be widened accordingly during assembly. This known arrangement requires relatively large guide lengths for the focusing member in the barrel and correspondingly high adjustment forces.